Vector monitor
Encyclopedia
A vector monitor or vector display is a display device used for early computers. It is a type of CRT
, similar to the oscilloscope
, but typically uses magnetic, rather than electrostatic, deflection. Here, the beam traces straight lines between arbitrary points, repeatedly refreshing the display as quickly as possible.
Vector displays for computers did not suffer from the display artifacts of aliasing
and pixelation
, but were limited in that they could display only a shape's outline (advanced vector systems could provide a limited amount of shading), and only a limited amount of crudely-drawn text (the number of shapes and/or textual characters drawn was severely limited, because the speed of refresh was roughly inversely proportional to how many vectors needed to be drawn).
Notable among vector displays were Tektronix large-screen computer terminals that used direct-view storage CRTs. Storage meant that the display, once written, would persist for several minutes before needing an erase and redraw cycle. (The CRT had at least one flood gun, and a special type of display screen, more complicated in principle than a simple phosphor.)
Vector displays were used for head-up display
s in fighter aircraft, because of the brighter displays that can be achieved by moving the electron beam more slowly across the phosphor
s. Brightness is critical in this application because the display must be clearly visible to the pilot in direct sunlight.
Vector monitors were also used by some late-1970s to mid-1980s arcade games such as Asteroids. Atari
used the term Quadrascan to describe the technology when used in their video game arcades.
Hewlett-Packard
made a large-screen fast vector monitor, which they called an X-Y display. It used a wide-angle electrostatically-deflected CRT that was about as compact as a magnetic-deflection CRT. Instead of the deflection plates of a typical CRT, it had a unique structure they called an electrostatic deflection yoke, with metallized electrodes inside a glass cylinder.
"). In these dual-layer tubes, by controlling the strength of the electron beam, electrons could be made to reach (and illuminate) either or both phosphor layers, typically producing a choice of green, orange, or red. Atari used the term Color Quadrascan to describe this color version when used in their video game arcades.
Tektronix made color oscilloscopes for a few years using penetration CRTs, but they apparently weren't in great demand.
Cathode ray tube
The cathode ray tube is a vacuum tube containing an electron gun and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms , pictures , radar targets and...
, similar to the oscilloscope
Oscilloscope
An oscilloscope is a type of electronic test instrument that allows observation of constantly varying signal voltages, usually as a two-dimensional graph of one or more electrical potential differences using the vertical or 'Y' axis, plotted as a function of time,...
, but typically uses magnetic, rather than electrostatic, deflection. Here, the beam traces straight lines between arbitrary points, repeatedly refreshing the display as quickly as possible.
Vector displays for computers did not suffer from the display artifacts of aliasing
Aliasing
In signal processing and related disciplines, aliasing refers to an effect that causes different signals to become indistinguishable when sampled...
and pixelation
Pixelation
In computer graphics, pixelation is an effect caused by displaying a bitmap or a section of a bitmap at such a large size that individual pixels, small single-colored square display elements that comprise the bitmap, are visible to the eye...
, but were limited in that they could display only a shape's outline (advanced vector systems could provide a limited amount of shading), and only a limited amount of crudely-drawn text (the number of shapes and/or textual characters drawn was severely limited, because the speed of refresh was roughly inversely proportional to how many vectors needed to be drawn).
Notable among vector displays were Tektronix large-screen computer terminals that used direct-view storage CRTs. Storage meant that the display, once written, would persist for several minutes before needing an erase and redraw cycle. (The CRT had at least one flood gun, and a special type of display screen, more complicated in principle than a simple phosphor.)
Vector displays were used for head-up display
Head-Up Display
A head-up display or heads-up display is any transparent display that presents data without requiring users to look away from their usual viewpoints...
s in fighter aircraft, because of the brighter displays that can be achieved by moving the electron beam more slowly across the phosphor
Phosphor
A phosphor, most generally, is a substance that exhibits the phenomenon of luminescence. Somewhat confusingly, this includes both phosphorescent materials, which show a slow decay in brightness , and fluorescent materials, where the emission decay takes place over tens of nanoseconds...
s. Brightness is critical in this application because the display must be clearly visible to the pilot in direct sunlight.
Vector monitors were also used by some late-1970s to mid-1980s arcade games such as Asteroids. Atari
Atari
Atari is a corporate and brand name owned by several entities since its inception in 1972. It is currently owned by Atari Interactive, a wholly owned subsidiary of the French publisher Atari, SA . The original Atari, Inc. was founded in 1972 by Nolan Bushnell and Ted Dabney. It was a pioneer in...
used the term Quadrascan to describe the technology when used in their video game arcades.
Hewlett-Packard
Hewlett-Packard
Hewlett-Packard Company or HP is an American multinational information technology corporation headquartered in Palo Alto, California, USA that provides products, technologies, softwares, solutions and services to consumers, small- and medium-sized businesses and large enterprises, including...
made a large-screen fast vector monitor, which they called an X-Y display. It used a wide-angle electrostatically-deflected CRT that was about as compact as a magnetic-deflection CRT. Instead of the deflection plates of a typical CRT, it had a unique structure they called an electrostatic deflection yoke, with metallized electrodes inside a glass cylinder.
Color displays
Some vector monitors are capable of displaying multiple colors, using two phosphor layers (so-called "penetration colorPenetron
The penetron, short for penetration tube, is a type of limited-color television used in some military applications. Unlike a conventional color television, the penetron produces a limited color gamut, typically two colors and their combination...
"). In these dual-layer tubes, by controlling the strength of the electron beam, electrons could be made to reach (and illuminate) either or both phosphor layers, typically producing a choice of green, orange, or red. Atari used the term Color Quadrascan to describe this color version when used in their video game arcades.
Tektronix made color oscilloscopes for a few years using penetration CRTs, but they apparently weren't in great demand.